Unicode URL Escapes in PHP

(The wirdz online dictionary can be found at wirdz.com.)

The standard method in for getting the value of a URL parameter is to use the $_GET array which is automatically created.

Unfortunately, the process which generates the array assumes that the URL only contains ASCII and escaped ASCII values. i.e. it doesn't handle Unicode escapes properly. So you need to get the value directly from the query string.

The following function returns a query string value (the alternative is to create an array first - more efficient for a long query string with more parameters):

function getQueryParameter ($strParam) {
  $strQueryString = $_SERVER['QUERY_STRING'];
  $aParamList = explode('&',$strQueryString);
  $i = 0;
  while ($i < count($aParamList)) {
    $aParam = split('=', $aParamList[$i]);
    if ($strParam == $aParam[0]) {
      return $aParam[1];
    } 
    $i++; 
  }
  return "";
}

The following function pair can be used then the convert the parameter value to Unicode (note in order for the Unicode values to display correctly on a generated HMTL page - the meta command <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> needs to be included in the page.):

function code2utf($num){
  if($num<128 br="">    return chr($num);
  if($num<2048 br="">    return chr(($num>>6)+192)
          .chr(($num&63)+128);
  if($num<65536 br="">    return chr(($num>>12)+224)
          .chr((($num>>6)&63)+128)
          .chr(($num&63)+128);
  if($num<2097152 br="">    return chr(($num>>18)+240)
          .chr((($num>>12)&63)+128)
          .chr((($num>>6)&63)+128)
          .chr(($num&63)+128);
  return '';
}

function unescape($strIn, $iconv_to = 'UTF-8') {
  $strOut = '';
  $iPos = 0;
  $len = strlen ($strIn);
  while ($iPos < $len) {
    $charAt = substr ($strIn, $iPos, 1);
    if ($charAt == '%') {
      $iPos++;
      $charAt = substr ($strIn, $iPos, 1);
      if ($charAt == 'u') {
        // Unicode character
        $iPos++;
        $unicodeHexVal = substr ($strIn, $iPos, 4);
        $unicode = hexdec ($unicodeHexVal);
        $strOut .= code2utf($unicode);
        $iPos += 4;
      }
      else {
        // Escaped ascii character
        $hexVal = substr ($strIn, $iPos, 2);
        if (hexdec($hexVal) > 127) {
          // Convert to Unicode 
          $strOut .= code2utf(hexdec ($hexVal));
        }
        else {
          $strOut .= chr (hexdec ($hexVal));
        }
        $iPos += 2;
      }
    }
    else {
      $strOut .= $charAt;
      $iPos++;
    }
  }
  if ($iconv_to != "UTF-8") {
    $strOut = iconv("UTF-8", $iconv_to, $strOut);
  }   
  return $strOut;
}

This function was adapted from previously published code. It will handle either Unicode or ASCII escapes correctly.